Being in the early stages of romantic love tends to coincide with higher sexual frequency among couples, but the intensity of that love does not seem to matter as much as simply being in love. A recent scientific review summarizes the latest theories and survey data to explain exactly how romantic feelings relate to sexual activity among young adults. The review was published in the journal Current Sexual Health Reports.
Romantic love is a motivational state typically associated with a desire to find and keep a long-term partner. It involves a specific set of emotional, cognitive, and biological changes that usually last for the first year or two of a relationship. After this initial period, the intense feelings tend to settle into a calmer, more stable state known as companionate love.
Sexual frequency refers to the number of times a person engages in sexual activity over a specific timeframe, such as a week. Historically, studies have consistently shown that sexual frequency decreases as a romantic relationship gets older. This consistent drop in sexual activity over time suggests that the early phase of a romantic relationship is associated with higher sexual frequency compared to later stages.
Despite this widely accepted idea, direct evidence specifically linking the psychological state of romantic love itself to sexual frequency has been limited. To address this gap, the authors conducted a review of the latest scientific literature from the past five years.
Adam Bode, a university guest academic at the Evolution Lab in the Melbourne School of Psychological Sciences at the University of Melbourne, led the review. “This review emerged because I was invited to write the review on this topic for a specialty journal that reviews recent advances in sex and related topics,” Bode said. “Surprisingly, scientists have not tended to investigate sexual frequency in people experiencing romantic love.”
Bode noted that he and his co-authors had previously published a number of studies that provided insights into this topic, utilizing data from the Romantic Love Survey 2022. “All the data came from the Romantic Love Survey 2022, which is the world’s largest publicly available dataset of people experiencing romantic love,” Bode said. This massive survey included over fifteen hundred young adults from thirty-three countries who identified as being in love. “I collected a team of others with expertise in romantic love and sexual topics, and we wrote the review.”
Approaching the topic from a biological perspective helps map out exactly why human beings experience such strong physical urges during the beginning stages of romance. “Sex is understood to be one of the evolutionary functions of romantic love, but no one had bothered to really investigate this empirically,” Bode said. “My colleagues and I are the first to do this.”
A major evolutionary theory explored in the review proposes that romantic love co-opted the neurobiological and endocrinological systems originally used for mother-infant bonding. This theory, detailed in a paper published in the journal Frontiers in Psychology, challenges an older model proposed by anthropologist Helen Fisher. Fisher’s older theory categorized sex drive, romantic attraction, and attachment as completely distinct and independently evolved emotion systems.
The newer perspective suggests that ancient brain systems responsible for human attachment merged with pre-existing reproductive systems, such as courtship attraction and sexual desire. Both maternal bonding and romantic love involve intense emotional connections, a strong drive for physical closeness, and a deep focus on the loved object.
Behaviors observed in both types of relationships include proximity-seeking, exclusive attention, and a heightened sense of empathy and responsibility. For instance, the obsessive thoughts about an infant seen in new mothers closely mirror the constant preoccupation with a romantic partner, suggesting common underlying mechanisms. By proposing that romantic love is an evolutionarily repurposed adaptation, this theory presents a paradigm shift in understanding the complex roots of human bonding.
Brain imaging studies provide evidence for this shared background, showing that the same reward circuitries are activated in both states. For example, the ventral tegmental area, a brain region linked to pleasure and motivation, is highly active in both romantic and maternal love. Regions rich in receptors for oxytocin and vasopressin, which govern emotional and social behaviors, also light up in both types of bonding.
Hormonal patterns provide additional evidence for this evolutionary overlap. Higher levels of oxytocin are found in individuals during the early stages of romantic relationships, matching the levels seen in new mothers following childbirth. Nicknamed the love hormone, oxytocin facilitates bonding and social recognition in both parent-child and romantic relationships.
When reviewing recent survey data, the authors found an apparent link between early romantic love and physical intimacy. “We now have decent evidence that sexual frequency is substantially increased in people experiencing romantic love,” Bode said. “The way we measured it was not ideal, but indications are that young adults are having sex about 3.5 times per week, with substantial variation including some people having sex up to 20 times per week.”
Bode noted this number is notably higher than the average sexual frequency found in the general married American population. “This is much more than the 1-2 times per week long-term married couples experience,” he said.
To dive deeper into the survey results, the researchers focused specifically on participants who had been in love for less than two years to capture the effects of early romantic passion. They looked at how different aspects of love, such as obsessive thinking about a partner or the intensity of feelings, affected sexual frequency. Unexpectedly, the intensity of a person’s romantic love did not predict how often they had sex.
Features like commitment levels, relationship duration within that two-year window, and obsessive thoughts also failed to predict sexual frequency. Only a tiny fraction of the variation in sexual activity could be explained by these specific relationship traits. This suggests that the basic state of being in love is associated with higher sexual frequency, rather than how strongly a person feels that love.
Brain imaging research supports this idea, showing that as a relationship progresses toward the one-year mark, sexual frequency tends to drop even if the intensity of the love remains high. The review also highlights that there is massive variation in sexual frequency among individuals in love. Bode actually found the overall numbers lower than he anticipated.
“To be honest, I was a little surprised the average frequency of sex among young adults experiencing romantic love was so low,” Bode said. “In my personal experience, when I was young and in love, I was having sex that often each day. So I guess I’m a bit of an outlier.”
To better understand this variation, a separate study published in the journal Personality and Individual Differences used a statistical method called cluster analysis on the survey data. Cluster analysis groups individuals based on shared characteristics. The researchers identified four distinct subtypes of romantic lovers: mild, moderate, intense, and libidinous.
The mild lovers, making up about twenty percent of the sample, had the lowest scores across romantic intensity, obsessive thinking, and commitment. This group showed the lowest agreeableness and extraversion traits and had the highest proportion of individuals diagnosed with Autism Spectrum Disorder, or ASD. They also reported the poorest health and functioning, the highest drug and alcohol use, the most risky driving habits, and the most unreciprocated love.
Moderate lovers made up the largest group at about forty-one percent of the sample. They showed relatively average levels of emotional traits and sexual frequency. This group was mostly unexceptional, though they reported the highest levels of self-confidence and the lowest use of antidepressants.
Intense lovers, making up twenty-nine percent of the sample, reported the highest levels of romantic intensity, commitment, and obsessive thinking about their partner. This was the only group with a higher proportion of women than men. They reported the highest relationship satisfaction, the highest agreeableness and conscientiousness traits, and the lowest levels of unreciprocated love.
The libidinous group, making up nearly ten percent of the sample, reported average emotional traits but exceptionally high sexual frequencies. Participants in this highly active group had sex nearly ten times a week on average. Every single person in this cluster reported being sexually active, compared to lower percentages in the other groups.
Libidinous lovers also displayed distinct personality and lifestyle traits. They scored the highest in openness, reported feeling the most energetic, and expressed the strongest desires to travel. Additionally, they had the highest proportion of individuals in committed relationships who were not yet living together.
An interesting finding involved the use of a common type of antidepressant known as a selective serotonin reuptake inhibitor, or SSRI. These medications are widely known to cause sexual dysfunction and lower sex drive. Surprisingly, the libidinous lovers group actually had the highest proportion of individuals taking SSRIs at nearly thirteen percent.
Overall, young adults in love who were taking these antidepressants reported having sex just as frequently as those who were not taking the medication. The authors suggest that the intense biological and emotional state of romantic love might override the negative sexual side effects of the medication. Alternatively, people experiencing severe sexual side effects might simply be less likely to progress a relationship to the point of falling in love.
A few potential misinterpretations and limitations exist regarding these findings. Most of the data comes from young adults residing in western, educated, and industrialized nations. Because of this specific demographic, the findings might not naturally apply to older adults or individuals from vastly different cultural backgrounds.
Additionally, defining what constitutes sex was left completely up to the individual survey participants. What counts as sex can vary widely from person to person, often including a range of physical intimacy beyond just intercourse. “The way we measured sexual frequency is not ideal,” Bode said. “We asked participants how many times per week they had sex (sex is whatever you take it to mean).”
This open interpretation means that some people might have counted behaviors that others would not consider to be sex, creating potential inconsistencies in the data. “This asks people to estimate instead of giving a discrete number of times they had sex in the past 7 days,” Bode explained. “It’s not the end of the world, and our findings are still important, but we could measure sexual frequency better in future.”
A key limitation of the current research is that it generally only looks at one half of a romantic couple. Sexual activity inherently involves two people, and the sex drive of an individual’s partner likely plays a massive role in determining sexual frequency. Future research should aim to study both members of a couple to get a complete picture of how romantic love influences sexual behavior.
“Sexual frequency is an important area of research in relation to love,” Bode said. “I am currently working on a paper with colleagues from Europe and the UK which looks at sexual frequency in romantic relationships and how a common measure of love is associated at different relationship durations.”
Bode anticipates that the upcoming research will provide even more answers. “It’s going to be a very interesting paper when it’s published,” he said. Expanding the research to include older age groups could reveal whether these patterns hold true throughout a person’s entire life.
These insights offer helpful perspectives for couples therapy. Knowing that sexual frequency is linked to the basic state of being in love, rather than the intensity of the romance, can help therapists normalize the natural ups and downs in a couple’s physical intimacy. The apparent ability of romantic love to push through the side effects of antidepressants also opens new doors for clinical treatments.
The review, “Romantic Love and Sexual Frequency,” was authored by Adam Bode, Severi Luoto, Marta Kowal, and Fabio Cannas Aghedu.